Mobility load balancing (“MLB”) as a feature of a self-organizing network (“SON”) is used to correct traffic imbalance between network cells. MLB can be viewed from the perspective of offloading traffic only from an overloaded serving cell to under-loaded neighbor cells. In this situation, overload thresholds and under-load thresholds are configured and MLB is invoked once the threshold conditions are met. In live networks, situations may arise in which a serving cell becomes relatively loaded with respect to neighboring cells. Users in such a situation experience severe service degradation. At the same time, under-loaded neighboring cells are under-utilized, leading to a stark disparity in the quality of service (“QoS”) experienced by users across cells of same access network. MLB aims to correct such traffic imbalances by enabling mechanisms to allow for “load sharing” between cells such that an overloaded cell (also referred to as the “source cell”) can offload a portion of the traffic that it serves to relatively under-loaded neighbor cells (also referred to as “target cells”). In a multi-cell scenario, it becomes possible for a loaded cell to offload portions of the traffic that it serves to multiple collaborating target cells in order to improve cell-wide spectrum efficiency, QoS, and quality of experience (“QoE”), and reduce blocking probability within the loaded cell.
A small cell supports the ability to load-balance between cells in a grid (also referred to as “intra-tier MLB”) and can also support load-balancing with macro/pico cells (also referred to as “inter-tier MLB”). In other words, when one of the cells in the grid or across layer is in an overload situation, whether measured by metrics such as physical resource blocks PRBs, transport resources, number of UEs, cell throughput, CPU utilization, and/or memory consumption, the overloaded cell may offload a portion of its traffic to more lightly loaded neighbor cells. For effective MLB to occur, existing methods rely on cooperation between an overloaded cell and an under-loaded cell or cells. Cooperation may take the form of radio resource utilization information exchange (i.e., “PRBs”) and mobility parameter information exchange (i.e., handover parameters) between a source cell and target cell(s). In LTE, handover parameters at the source base station, such as cell individual offset (“CIO”) and cell frequency offset (“CFO”) can be biased (i.e., reduced or increased) relative to neighbor cells to which it intends to load balance (i.e., shed) its users.